Secondary battery and method for manufacturing same

Abstract

A secondary battery includes: an electrode assembly including a positive electrode tab; and a case surrounding around the electrode assembly, and including: an accommodation portion accommodating the electrode assembly; a positive electrode terminal protruding from the accommodation portion in a first direction, and electrically connected to the positive electrode tab; and an upper flange extending from the accommodation portion in the first direction. A shortest length of the upper flange extending from the accommodation portion in the first direction is less than a length of the positive electrode terminal protruding from the accommodation portion in the first direction.

What is claimed is: 
     
         1 . A secondary battery comprising:
 an electrode assembly comprising a positive electrode tab; and   a case surrounding around the electrode assembly, and comprising:
 an accommodation portion accommodating the electrode assembly; 
 a positive electrode terminal protruding from the accommodation portion in a first direction, and electrically connected to the positive electrode tab; and 
 an upper flange extending from the accommodation portion in the first direction, 
   wherein a shortest length of the upper flange extending from the accommodation portion in the first direction is less than a length of the positive electrode terminal protruding from the accommodation portion in the first direction.   
     
     
         2 . The secondary battery as claimed in  claim 1 , wherein the upper flange comprises:
 a terminal region corresponding to the positive electrode terminal; and   edge regions on opposite side surfaces of the terminal region,   wherein a length in the first direction of an edge region of the edge regions is greater than a length of the terminal region in the first direction.   
     
     
         3 . The secondary battery as claimed in  claim 2 , wherein the length of the edge region in the first direction is greater than the length of the positive electrode terminal protruding from the accommodation portion in the first direction. 
     
     
         4 . The secondary battery as claimed in  claim 2 , wherein a length of the terminal region in a second direction perpendicular to the first direction corresponds to a length of the electrode assembly in the second direction. 
     
     
         5 . The secondary battery as claimed in  claim 2 , wherein a length of the terminal region in a second direction perpendicular to the first direction corresponds to a length of the positive electrode terminal in the second direction. 
     
     
         6 . The secondary battery as claimed in  claim 1 , wherein the upper flange comprises:
 a terminal region corresponding to the positive electrode terminal; and   edge regions on opposite side surfaces of the terminal region,   wherein a length in the first direction of an edge region of the edge regions is equal to a length of the terminal region in the first direction.   
     
     
         7 . The secondary battery as claimed in  claim 1 , wherein the electrode assembly further comprises a negative electrode tab,
 wherein the case further comprises a negative electrode terminal protruding from the accommodation portion in the first direction, and electrically connected to the negative electrode tab,   wherein the upper flange comprises:
 a first terminal region corresponding to the positive electrode terminal; 
 a second terminal region corresponding to the negative electrode terminal; 
 a middle region between the first terminal region and the second terminal region; and 
 edge regions on an outer side surface of the first terminal region and an outer side surface of the second terminal region, respectively, and 
   wherein lengths of the first terminal region and the second terminal region in the first direction are less than lengths of the middle region and the edge regions in the first direction.   
     
     
         8 . The secondary battery as claimed in  claim 1 , wherein the case comprises:
 a main body having one opened side, and comprising the accommodation portion and the positive electrode terminal; and   a cover joined to the one opened side of the main body.   
     
     
         9 . The secondary battery as claimed in  claim 8 , wherein the cover comprises a protrusion protruding in a third direction and joined to the main body. 
     
     
         10 . The secondary battery as claimed in  claim 9 , wherein a length of the protrusion in the third direction corresponds to a thickness of the main body in the third direction. 
     
     
         11 . The secondary battery as claimed in  claim 9 , wherein a length of the protrusion in the first direction is 0.1 mm to 0.2 mm. 
     
     
         12 . The secondary battery as claimed in  claim 9 , wherein corners of the protrusion have a straight-angled shape or a curved shape. 
     
     
         13 . The secondary battery as claimed in  claim 1 , wherein the case further comprises:
 a lower flange extending from the accommodation portion in a direction opposite to that of the upper flange; and   a side flange extending in a second direction perpendicular to the first direction.   
     
     
         14 . The secondary battery as claimed in  claim 1 , wherein a thickness of the upper flange is 0.1 mm. 
     
     
         15 . The secondary battery as claimed in  claim 1 , wherein the case comprises stainless steel (SUS). 
     
     
         16 . A method for manufacturing a secondary battery, the method comprising:
 preparing an electrode assembly comprising a positive electrode tab, and a main body comprising:
 an accommodation portion in which the electrode assembly is accommodated; and 
 a positive electrode terminal protruding from the accommodation portion in a first direction, and electrically connected to a positive electrode tab; 
   positioning the electrode assembly in the main body;   forming a case by welding a cover to one opened side of the main body; and   laser cutting a flange of the case,   wherein, after the laser cutting, the case comprises an upper flange extending from the accommodation portion in the first direction, and a shortest length of the upper flange extending from the accommodation portion in the first direction is less than a length of the positive electrode terminal protruding from the accommodation portion in the first direction.   
     
     
         17 . The method as claimed in  claim 16 , wherein after the laser cutting, the case comprises:
 a lower flange extending from the accommodation portion in a direction opposite to that of the upper flange; and   a side flange extending in a second direction perpendicular to the first direction.   
     
     
         18 . The method as claimed in  claim 16 , wherein the forming of the case comprises joining the cover to the main body in a third direction,
 wherein the cover comprises a protrusion protruding in the third direction and joined to the main body.   
     
     
         19 . The method as claimed in  claim 16 , wherein the upper flange comprises:
 a terminal region corresponding to the positive electrode terminal; and   edge regions on opposite side surfaces of the terminal region,   wherein a length in the first direction of an edge region of the edge regions is greater than a length of the terminal region in the first direction.   
     
     
         20 . The method as claimed in  claim 19 , wherein the laser cutting comprises laser cutting the edge regions except for the terminal region.